Fuel sys. Pressure Test Q's>>

[Mkid]

I have a walbro thats about 2 year's old and a KB AFPR.

Before I installed my 50lbers...when i prrimed the fuel pump the pressure would go up to its setting{40lbs} and hold for a long time{overnight}.

But now with the 50lbers on >>the pressure goes up and starts droping down...sometimes all the way to 4psi and/ sometimes it holds at its setting.notence started the truck runs fine.

How do I rule out injectors/AFPR/fuelpump as the cause?? I have the intake off to repair a cyclinder head and was planning to prime the pump with the intake off so i could look at the injectors to see if they are bleeding down before start up...>

If an injectors is leaking after prime, i should replace it..right??

If the injectors arn't leaking, how do I tell if its the fuel pump or the regulator??

 

[ghettosled]

I know most of the fpr's like the weldon, aeromotive, etc dont hold pressure after you kill the fuel pump. i wouldn't sweat it as long as your fp is steady at WOT.

 

[turbodog]

If you want to be sure, the test sequence goes like this:

1. run pump using 'prime' connector. clamp retun line to pinch it closed at the rubber section at bottom of firewall. Turn pump off. If pressure now holds, it's the regulator allowing pressure bleed-off.

2. run the pump. clamp the fuel feed line at bottom of firewall. turn pump off. If pressure now holds, it is the check valve in the pump that is allowing bleed-off.

If the pressure fails to hold in either test, the injectors are leaking.